DESCRIPTION Abstract: Long-term objectives: The proposed studies will ask whether chromosome positioning can inform us about three puzzling patterns of inheritance: missing heritability, acquired traits, and transgenerational inheritance. It represents a major departure from the questions that are usually posed with respect to chromosome positioning, but can be justified by what we currently know about inheritance, epigenetics, and the tremendous capacity of chromosome positioning to affect gene expression and chromosome behavior. The studies will use two new technologies: high-throughput fluorescent in situ hybridization (FISH) and Oligopaints, which have been designed to reduce the cost of FISH while increasing resolution. Health relatedness: Chromosome positioning is a potent regulator of gene expression; proximity of chromosomal regions can direct chromosome rearrangements, the location of genes within the cen- tral or peripheral parts of the nucleus is associated with different levels of gene expression, and ap- position of chromosomal regions can activate and silence genes. As these processes are essential for normal human development, the studies proposed here on chromosome positioning will have direct relevance to human health. In addition, the potential that chromosome positioning may account for some puzzling forms of heritability brings additional potential for this study to contribute to our under- standing of disease and, therefore, the design of strategies to improve health. Innovation: This application proposes a new concept, that chromosome positioning may be able to account for some puzzling forms of inheritance. It also introduces two new technologies using fluo- rescent in situ hybridization (FISH) that are appropriate for the analysis of many types of chromosome positioning. The first is a technology for high-throughput FISH, permitting a single individual to process up to 3,000 FISH assays per day, and the other, called Oligopaints, is a new type of probe th